Section 18 and 19 Flashcards
Wave basics
Transverse – vibrate at perpendicular angles to direction- vibrations go up and down
Longitudinal- vibrate parallel to direction that the wave travels - vibrations go side to side
Waves transfer energy and information in direction they are traveling
Measuring waves
Oscillioscope measures speed of sound – use 2 microphones aswell to find wavelength of sound generated
Water ripple tank – wavelength, divide length of tank by number of waves
Frequency – count how many waves passing a point in 10 seconds then divide by 10
Use peak frequency to find speed of waves in solids – record length metal rod,tap road with hammer, record peak frequency, repeat three times
Ripple tank practical
Set up ripple tank so dipper vibrates on water surface to create waves
Adjust frequency so you can see individual waves
Measure wavelength and then frequency
Wave speed = frequency X wavelength
Refraction of light practical
Draw around prism on paper
Draw a normal line (perpendicular)
Use a protractor to measure 10° from normal and mark it on
Direct Ray box so light goes into block at 10°
Draw where light ray comes out of block
Measure angle of refraction
Repeat from different angles
Wave behaviour at boundaries
Waves are absorbed by the second material
Wave is transmitted through second
Wave is reflected – neither episode or transmitted
Refraction
If wave hits Boundry at angle, change of speed causes change in direction
Wait beans towards normal is slows down, Ben is away from normal it speeds
Waves travel at different speeds with different densities
How much a wave refracts depends on its wavelength
Electromagnetic waves
They’re transverse waves
Yeah on way to transfer energy from source to absorb – higher the frequency more energy
Long wavelength, low frequency – radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays – short wavelength, high frequency
Em waves uses
Radio waves–communication, broadcasting and satellites
Microwaves – satellites, heat food, heats cells internally
Infrared – increase/monitor temp, transfer info, thermal vision
Visible light - photography, to see, causes blindness
Ultraviolet-fluorescent lamps, telling salons, ionising, cause cancer
X-rays – scanning inside, search for cancer, ionising, cause cancer
Gamma – Sterilising, treating cancer, ionising, cause cancer
The atom
Nucleus – contains protons and neutrons
Protons = relative mass = 1, relative charge +1
Electron = relative mass = 1/1837, relative charge = -1
Neutron = relative mass = 1, relative charge = 0
Plum pudding method
Fired alpha particles at thin gold foil
Someone through some were reflected
Rutherford’s method
Have a password affected by nucleus, shows positively charged (nucleus) and its dense
Most particles went straight through undetected, shows atom is made up of space
Some alpha particles were attracted towards electron, shows they are negative
Electron energy levels
An atom is ionised if it loses an electron
Nuclear radiation Ionises atoms
Alpha
Nucleus sluices two protons and two neutrons
Nuclear number = – 4
Proton number = – 2
Strong ionisation, least penetrating, stop by paper
Beta minus
Nucleus – one neutron turns into one proton and releases an electron
Nuclear number = same
Proton number = +1
Medium ionisation, medium penetration, stop by aluminium
Beta plus
Nucleus – one proton turns into a neutron, positron is released
Nucleon number = same
Proton number = –1
Medium ionisation, medium penetration, stopped by aluminium
